From U.S. Pat. No. 4,144,798 of the Applicant, a fluid pressure unit with a cylinder block is known which has radial bores of rectangular cross section. Each piston has a piston cap periodically exposed to pressure from a medium and a roller supported on the piston cap. The rollers are supported on a cam surrounding the cylinder block and producing at least one stroke. Each roller, together with a first of the two side walls of the radial bore disposed perpendicular to the direction of rotation, forms a variable gap, and each piston cap forms a sealing point together with the second of the two side walls. An intermediate pressure chamber exposed to the pressure of the medium is located between the variable gap and the piston cap along the first side wall.
In this known fluid pressure unit, pressure distributions are attained at the rollers which effect the deflection of force, these pressure distributions simultaneously effecting the establishment of the variable gap and the transmission of the torque force. The two structural components of each piston, namely the piston cap and the roller, accordingly function within the rectangular piston bore both in a sealing fashion and, by the creation of suitable pressure fields, in a force-transmitting fashion.